Gas burner



4 Sheets-Sheet l L. E. PEARCH ETAL GAS BURNER Sept. 13, 1966 Filed Nov. 1e. 1964 INVENTORS. I OVELL E. PEARCIH PETER P. SURCKLA BYw/, SSS/13, Mm M ATTORNEYS.

llllilT.. :im

Sept. 1.3, 1966 5 PEARCH ETAL 3,272,440

I6 28 25 29 18 '7 5 Il @m www a7 23 l1 2e Q INVENTORS. LOVELL. E. PEA RCH PETER P. SURCKLA BYSQ/v, ssras,

ATTORNEYS Sept. 13, 1966 E PEARCH ETAL 3,272,440

GAS BURNER Filed NOV. 16, 1964 4 Sheets-Sheet .'5

.Il N Nk $00000 OOO Q55. Mm

III I l 1| lll! rl Tllal hf #E t l. r Il. I h I...| .l I I; :\\.1\:\: l i.E:,.HEN uw- T x N w .Q l IIII 'I I I I I I I Ill-I |||||+;1 I I I I l I -Ik lll/f Sept. 13, 1966 L. E, PEARCH ETAL 3,272,440

GAS BURNER Filed Nov. 1e, 1964 4 sheets-sheet 4 www I* ll- 'IIII -III III -M-II B PE 7753 P SCJACKL@ Y @ma/Swag.. LIE LT Maf/s :IM

ATTORNEYS.

United States Patent O 3,272,440 GAS BURNER Lovell E. Pearch, Westlake, and Peter l. Surclrla, Burton, Ohio, assignors to Rex-Radiant, Inc., Cleveland, hio, a corporation of Ohio Filed Nov. 16, 1964, Ser. No. 411,357 21 Claims. (Cl. Z39- 426) This invention relates to gas-fired, open flame burners and particularly to such burners known as ribbon burners. Such burners have a long and relatively much narrower combustion zone and correspondingly proportional means for supplying a combustible mixture to the zone so that a narrow, generally continuous ribbon of flame is provided along the combustion zone.

Operating conditions involving high ambient temperatures and atmospheres low in oxygen are frequently encountered in certain heater or burner applications and particularly in industrial applications such as industrial ovens, die casting apparatus and the like. Such openating conditions are generally the direct result of the operation of many burners or heat-producing devices. Gas-fired heaters operating under these conditions suffer in their performance from a lack of oxygen to support complete combustion and from a tendency to backfire due to the unintended raising of a combustible mixture in or being supplied to the burner to the ignition temperature of the mixture before it is intended to be burned or before it reaches the intended combustion zone.

The primary object of this invention is to provide a gasred, open llame ribbon burner suitable for burning large quantities of gaseous fuel to provide yhigh outputs in high ambient temperatures and in atmospheres having reduced amounts of oxygen without diminution of the burners performance in the manner described above. Another object is to provide such a burner which does n-ot permit combustion of a flammable mixture of gaseous fuel and air except in the intended combustion zone. Another object of this invention is to provide such a burner that is particularly well adapted to be constructed and operated in a relatively narrow and longitudinally extending configuration so `as to provide a long strip or ribbon of high heat output. Still a further object is to provide such a burner which insures the even distribution of gaseous fuel from one end of the burner to the other so that a relatively even flame exists along the length of the burner and the heat output does not vary in any substantial amount throughout its length. Another object of this invention is to provide a long open flame ribbon-type burner having a well defined longitudinally extending cornbustion zone and means to separately introduce into the combustion zone the necessary quantities of gaseous fuel and air to insure high outputs of heat from the burner, useful, for example, for heating nozzles of die casting apparatus. Yet another object is to provide a burner having such -a combustion zone together with means for insuring uniform distribution of `the `supply of gaseous fuel to the zone and particularly throughout its length and also to insure the delivery of adequate quantities of air for combustion of the gaseous fuel so as to accomplish complete and uniform mixing of the gaseous fuel and air within the combustion zone and without disturbing the even and uniform burning of the flame along the length of the burner. Yet another object is to provide a ribbon burner having such a combustion zone and including means for defeating any tendency of the flame to be blown or bent toward one end of the burner or the other by the incoming air supply and/or `gaseous fuel supply as well as means for terminating each end of the llame ribbon cleanly and without any feathering or tailing. A general object of this invention is to provide an open flame ribbon burner capable of accomplishing the objects mentioned above and, in addition, a burner able 3,272,440 Patented Sept. 13, 1966 to be relatively easily manufactured and assembled for use so as to provide a simple and economical, yet highly effective, commercial burner.

Briefly, the foregoing objects are accomplished, at least in part, by a burner having a walled combustion zone that is relatively much longer than it is wide and which has a longitudinally extending open side or face along and from which a high output ribbon of open flame lappears because of the combustion of gaseous fuel and air supplied to the combustion zone. Further, gaseous fuel unmixed with air is introduced directly into the combustion zone through a longitudinally extending inlet port in that side or face of the combustion zone substantially opposite and away from its open face. The burner includes means outside the combustion Zone for accomplishing the uniform distribution of gaseous fuel to and along the length of its inlet port into the combustion zone. Air for combustion of the gaseous fuel is introduced into the combustion zone through ia pair of longitudinally extending air inlet means or ports. The air inlet means lie on opposite sides of the longitudinally extending gas inlet port and are substantially parallel thereto and to each other. Further, the air inlet means are arranged with respect to each other and ahe gas inlet port to insure the thorough and uniform mixing of the flammable mixture in the combustion zone. Means are provided outside the combustion zone for insuring that the volumes and pressure of the air being introduced into the combustion zone is the same at both air inlet means.

From the foregoing brief explanation, it will be apparent that any tendency for combustion to occur in the burner other than in its combustion zone is effectively prevented by maintaining the principal constituents of the flammable mixture, i.e. the gaseous fuel and air, separate and apart from each other and mixing them together only in the combustion zone. It will further be apparent that `such a burnner as briefly described above has an adequate supply of air to support combustion and thus does not depend upon atmospheric oxygen for its proper operation.

Other features and advantages of this invention will be apparent from the following detailed description -of a preferred form of burner embodying the invention and the accompanying drawings in which:

FIGURE 1 is a partially sectioned plan elevation view of such a gas burner;

FIGURE 2 is a partially sectioned side elevation view of the burner shown in FIGURE l;

FIGUR-E 3 is an end elevation view of the burner shown in FIGURE 2 and taken as indicated by the line 3--3 thereon;

FIGURE 4 is ian almost complete longitudinal sectional view of the burner shown in FIGURE l taken in the plane of line A'-i-Ll and in enlarged scale;

FIGURE 5 is a transverse section through the burner shown in FIGURE 2 taken in the plane of line 5-5 and in enlarged scale;

FIGURE 6 is a partially sectioned plan elevation view of a modification of the burner in FIGURES 1 through 5;

FIGURE 7 is a partially sectioned side elevation view of the burner shown in FIGURE 6;

FIGURE 8 is a transverse section through the burner shown in FlGURE 6 taken in the plane of line 8-8 and in enlarged scale;

FIGURE 9 is a partially sectioned p-lan elevation View of another modified form of gas burner embodying this invention;

FIGURE 10 is a partially sectioned side elevation view of the burner shown in FIGURE 9;

FIGURE 1l is a transverse section through the burner shown in FIGURE 9 taken in the plane of line 11-11 and in enlarged scale; and

FIGURE 12 is a transverse section through yet another modified burner embodying this invention and is a view similar to that shown in FIGURES 5, 8, and ll of other forms of this invention.

The burner structure embodying this invention and shown in FIGURES l through 5 of the drawings comprises two main elements; an air manifold indicated generally at and a gaseous fuel manifold indicated generally at 11.

Air manifold 10 consists of a pair of generally similar longitudinally extending hollow conduits 12 arranged in parallel spaced apart fashion. The adjacent ends of the two conduits 12 are joined together by short transverse hollow conduits 14. This joining together of the longitudinally extending conduits 12 and the transverse conduits 14 places the interior passages of the hollow conduits in communication with each other so that, together, they form a continuous closed path or passage indicated generally at 15.

Air manifold 10 is provided with an air supply means consisting of an opening 16 in the external wall 17 of one of the short transverse hollow conduits 14 and an interiorly-threaded bushing 18 fastened to the exterior side of wall 17 as by welding. Bushing 18 merely provides a means for connecting an air supply line to the burner and any suitable means for accomplishing this purpose may be employed. It will be noted that air supplied to air manifold 10 through opening 16 enters about the middle of and perpendicular to the length of one of the shorter transverse conduits 14 so that it strikes the nearby opposite wall of conduit 14 and is slowed down.

The inside longitudinally extending side walls 19 of each of longitudinally extending conduits 12 of air manifold 10 are provided with air inlet means comprising a plurality of holes or passages 20 spaced apart along their length. Preferably, the plurality of holes or passages 20 are arranged as shown in FIGURE 4 in two parallel spaced apart rows and the holes in one row are staggered with respect to the holes in the other row and are spaced from each other both within a row and between rows as closely as possible without breaking out the wall of material therebetween. It will be noted especially in FIGURE 5 that the passages 20 in the oppositely facing inside side walls 19 of the two conduits 12 are aimed transversely across the burner at each other. Although the air inlet means employed in one successful embodiment of this invention comprises a double row of closely spaced and staggered air holes as shown in the drawings, this invention comprehends other air inlet means which distribute and direct air normally out from along a longitudinally extending side of the longer conduits 12 and transversely of the space between conduits 12.

The inside walls 21 of the short transverse hollow conduits 14 are each provided with an air passage 22 located substantially midway between the inside walls 19 of longitudinally extending conduits 12. The passages 22 in the two ends of the burner are aimed substantially at each other and preferably lie in a plane spaced from the passages 20 in the side walls 19 of conduits 12 as shown in the drawings.

The operation of the air manifold and, in particular, the role played by passages 2t) and 22 in delivering air to the combustion zone of the burner will be described more fully below.

Gaseous fuel manifold 11 consists of a longitudinally extending hollow conduit 23 lying between and engaging the two parallel longitudinally extending conduits 12 and two shorter transverse hollow conduits 14 comprising air manifold 10. The ends of hollow conduit 23 are closed as by abutment with and attachment to inside walls 21 of transverse hollow conduits 14. The ends of hollow conduit 23, of course, may be closed and sealed in other ways. Face 24 of hollow conduit 23, i.e. the face of the conduit looking out from between inside walls 19 of conduits 12 and past passages 20 and 22 therein, is provided with a longitudinally extending gaseous fuel inlet means comprising a passage 25, preferably in the form of a slot extending almost from end to end of the face 24 of hollow conduit 23. Passage 25 comprises the means for introducing gaseous fuel in the combustion zone as will be described more fully below.

Preferably, hollow conduit 23 consists of hollow tubing of generally square transverse cross section as shown most clearly in FIGURE 5. Hollow conduit 23 of such a shape readily fits together with an air manifold consisting of conduits of a rectangular cross-sectional configuration.

Gaseous fuel is supplied to hollow conduit 23 of gaseous fuel manifold 11 through a gaseous fuel supply means comprising any conventional hollow connecting means such as exteriorly-threaded stub pipe 26 which enters and extends inwardly beyond outer wall 27 of hollow gaseous fuel conduit 23. A hollow tubular distributing conduit 28 is provided inside and concentric with hollow gaseous fuel conduit 23 in a manner shown most clearly in FIG- URES 4 and 5. Distributing conduit 28 extends from end to end of hollow conduit 23 and, as shown in the drawings, tightly abuts inside walls 21 of conduits 14 so as to form a substantially gas-tight seal. Stub pipe 26 extends through the wall of hollow tubular distributing conduit 28 and thus is adapted to supply gaseous fuel therein. A longitudinally extending distributing passage 29, preferably in the form of a long slot, is provided in the wall of distributing conduit 28 and is located on the opposite side of the gaseous fuel manifold 11 from gaseous fuel passage 25 in hollow conduit 23.

Tubular distributing conduit 28, as shown in FIG- URES l through 5, is preferably an exteriorly-threaded pipe of circular cross section. The outside diameter of the distributing `conduit 28 is preferably such that it engages the interior surface of the side walls of the square cross section hollow conduit 23 at its four points of tangency therewith. *In one successful form of the burner, t-he generally square interior of conduit 23 was enlarged slightly with a circular reamer which cut slightly transversely arcuate, longitudinally extending -grooves down the center of each of the longitudinally extending interior surfaces of the side walls. An exteriorlythreaded distributing conduit 28 of suitable diameter to snugly engage the reamer-produced grooves was then fitted into hollow conduit 23.

In operation, gaseous fuel is supplied through pipe stub 26 t-o the inside of distributing `conduit 28 of gaseous fuel manifold 11. The gaseous ,fuel passes out of distributing cond-uit 28 through longitudinally extending distributing passage or slot 29 facing the opposite side of hollow conduit 23 from that containing passage 25. Thence, the gaseous yfuel :flows both ways around the outside or exterior surface of distributing conduit 28 and particularly along and between the threads `cut therein. Even though the gaseous Ifuel enters at or near one end of the gaseous fuel manifold 11 and must necessarily acquire a vector of motion and of lvelocity toward t-he other end thereof, the gaseous Afuel is uniformly distributed to and along the length of passage `or slot 25 because of its countenflow pattern and its iiow through the transverse passages .between the threads of distributing conduit 28 and interior walls of conduit 23.

From the foregoing descriptions of the air manifold 10 and gaseous `fuel manifold 11 of the burner shown in FIGURES 1 through 5, it will be seen that they are structurally related and work together and cooperate to provide a combustion zone indicated generally at 30. Combustion zone 30 lies between inside side rwalls 19 and 121 of conduits y1'2 and 14, respectively, and face 24 of ygaseous fuel conduit 23. Combustion zone 30 is eiffectively walled and closed except `for one open side toward which passage 25 in gaseous fuel manifold 11 is directed.

The combustion zone of one successful burner ernbodying this invention and similar to the burner shown in FIGURES 1 through 5 is approximately 101/2 inches long, 1/2 inch wide and 3%: inch deep. Gaseous fuel passage 25 is a slot approximately l0.030 inch in width and each air passage is about l@ inch in diameter. Further, the centerline between two rows of air passages 20 in each longitudinally extending `conduit 12 is located a distance above the exterior sur-face of face 24 of hollow gas conduit 23 a distance approximately equal to one-half the width of combustion zone 3i). The single air passage 22 in walls 2 1 of shorter conduits 14 are located on the centerline of combustion zone 30 and slightly farther away from gaseous fuel passage 215 than the ilongitudinally extending rows of holes constitutin-g air passages 20.

Air to support combustion of the gaseous fuel supplied to combustion zone l30 is introduced through bushing 118 and opening 16 into one of the short transverse ends of air manifold 10. The air generally is divided and flows down and fills both parallel longitudinally extending hollow conduits 12. Shorter transverse hollow conduits l14 at each end of longer conduits 12 insure the equalization of pressure from side to side and from end to end of the air. As mentioned previously, air passages 20 `are directed transversely of combustion zone 30` and air issues from them in a rflow pattern normal to the length of combustion zone 30.

In burning, suiicient supplies of gaseous fuel and air are supplied to their appropriate manifolds in conventionally proportional amounts, eg. 1:10. The output of the burner may be `varied by increasing or decreasing the amounts of gaseous fuel and air supplied thereto. The burner burns with a strong, -straight ribbon of flame substantially -uniform throughout the ylength of the combustion zone 30.

The ends of the flame ribbon are sharp and clean and do not feather ror tail off. yIt is believed that this is `a direct result of air passages 22 in short transverse conduits '14.

Ilhe uniform distribution of the strength of the flame throughout the length of the combustion zone without any tendency lto blow or lean toward one end or the other end or waver between them is believed to result directly from the simple, yet unique, gaseous Afuel distribution arrangement provided by gaseous fuel manifold 11. In addition to the uniformity of the distribution achieved by the passa-ges between the threaded exterior of distributing conduit 28 and the interior of hollow conduit 23, it is believed that the uniformity of `gaseous fuel pressure throughout the length of the cornbustion zone is materially enhanced by the longitudinally extending small chambers `31 :formed in each corner of the square internal cross section of hollow -gas conduit 23. These hollow corner chambers 31, as seen in FIG- URE 5, result from the combination of the circular cross section distributing conduit 23 and the square cross section gaseous fuel conduit 23. Chambers 31 provide longitudinally extending equalizing passages crossing the otherwise transverse ifiow path of 'gaseous fuel between distributing passage 29 in distributing conduit 28 and outlet passage in conduit 23.

Another factor contributing to the uniform distribution and the burning within the `combustion zone is the thorough and complete mixture of the separately introduced gaseous fuel and air within the combustion zone. T'his thorough mixing is achieved principally by the flow of air into the combustion zones from opposite sides thereof and from the oppositely facing passages in the air conduits. The air rflows initially transversely of combustion zone and between gaseous fuel passage '25 in hollow conduit 213 and the open face of the combustion zone so that gaseous fuel issuing from manifold 11 impinges `on and passes through and is mixed with the supply of air provided.

A further advantage of the oppositely directed air passages is that the air issuing 'from them tends to keep the gaseous fuel passage 2S in gaseous fuel conduit 23 `free of lforeign matter that might drop into the burner and combustion Zone l3l) through .its open face. yIn especially dirty atmospheres, the air supply can advantageously be maintained even when the burner is not burning and the gaseous fuel supply is shut off in order to keep the `outlet passages clean.

From the foregoing, it will be -readily apparent that combustion elsewhere than in the combustion zone of the burner is impossible because it is only in the combustion zone tha-t a flammable mixture of gaseous fuel and air is present. Thus, backring or premature ignition in zones other than the desired combustion Zone: is impossible. Further, because the burner is provided with its own supply of combustion-supporting air, the burner can be operated in atmospheres without regard to the oxygen content thereof. Burners embodying this invention comprise apparatus useful singly or in groups arranged lengthwise and side by side. One application in which burners embodying this invention have been most useful is as nozzle heaters for die casting apparatus. Further, the burner can be used in any position of orientation without materially affecting its performance.

FIGURES 6, 7, and 8 of the drawings show a modification or adaptation of the burner shown in FIGURES 1 through 5 of the drawings and described above. The modified burner is particularly adapted for use in longer burners to insure an adequate gas supply when their length becomes too great to permit satisfactory ope-ration of the usual arrangement for supplying gas shown in FIG- URES 1 through 5. There are similarities in the two forms of burne-rs and corresponding and like elements of the two burners shown in FIGURES 1 through 5 and in FIGURES 6 through 8 are identified by the same reference numerals. It will be apparent that air manif-old 10 comprising two parallel spaced apart, longitudinally extending, hollow conduits 12 joined at their opposite ends by shorter transverse hollow 4conduits 14 is the same in both forms of the burner embodying this invention.

The primary difference between the preferred and modied forms is found in the form of gaseous fuel manifold employed. The gaseous fuel manifold 11 in the burner shown in FIGURES 1 through 5 comprises briefly hollow tubular distributing conduit 28 located within a larger hollow conduit 23. Gas is introduced into the interior passage of distributing conduit 28 at one end thereof through stub pipe 26 and passes therefrom through a longitudinally extending distributing passage 29 into conduit 23 for discharge into combustion zone 30 through passage 25. In the modified form of burner shown in FIG- URES 6 through 8, gas is supplied to a gaseous fuel manifold indicated generally at 32 through the interior of a hollow tubular distributing conduit 33 at a plurality of points spaced apart along its length rather than at one end only and/ or at a single point along its length. A larger hollow conduit 34 carries distributing conduit 33 within it and receives gas from it for discharge to the combustion zone in `the same manner as conduit 23 in FIGURES 1 through 5. The distributed introduction of gas into distributing conduit 33 is accomplished by a longitudinally extending gas plenum 35, preferably lying beneath and coextensive in length with gaseous fuel manifold 32. Gas plenum 35 is preferably of substantially greater crosssectional area than the passage in distributing conduit 33, e.g. ten times greater.

Gas is supplied plenum 3S through a gas pipe (not shown) connected to pipe bushing 37 opening into one end of the plenum or by other suitable means. The relatively greater volume of plenum 35 with respect to the volume of the passage and interior of distributing conduit 33 permits a volume and reservoir `of gas to be accumulated in the plenum substantially in excess of -that required to ll distributing `conduit 33. Thus, the How of gas lengthwise of plenum 35 is relatively slow and the pressure drop from one end to the other may be made quite small. Gas is permitted to pass from plenum 35 into the internal passage of distributing conduit 33 through a plurality of intercommunicating passages 36 spaced apart throughout the length of the plenum and conduit and passing through the adjacent walls of the plenum 35, hollow conduit 34, and distributing conduit 33.

A further modification of the burner shown in FIG- URES l through and described in connection therewith appears in FIGURES 9 through ll of the drawings and is described below. This burner, like the others, comprises an air manifold indicated generally at 40 and a gas manifold indicated generally at 4l. Air manifold 40 comprises a pair of laterally spaced apart, longitudinally extending, and generally parallel hollow conduits 42 joined together and placed into communication with each other at their opposite ends by shorter transverse hollow conduits 43. Spaced between laterally opposite longer conduits 42 and shorter transverse conduits 43 of air manifold `40 is gas manifold 41 which, together with conduits making up air manifold 40, forms a combustion zone indicated generally at 4S. As seen in cross section in FIG- URE ll, combustion zone 45 is closed on three sides by air and gas manifolds 40 and 4l and has an open face on the fourth side.

Contained within each of longer conduits 42 of the air manifold is a hollow distributing conduit 46 similar, for example, to hollow distributing conduit 2S provided in the gaseous fuel manifold of the burner shown in FIGURES l through 5. Distributing conduits 46 in air manifold 40 are preferably exteriorly-threaded pipes of circular cross section and have outside diameters which engage the surfaces of at least two opposite inside walls of the rectangular cross section hollow conduits 42. Hollow distributing conduits 46 are preferably located and lie against the upper inside surfaces -of conduits 42 with the external threads of distributing conduits 46 engaging the walls as clearly shown in FIGURE l1. Each distributing conduit 46 is provided with a longitudinally extending distributing passage 47. When distributing conduits 46 are located within conduits 42 as shown in FIGURE 11, distributing passages 47 are arranged to discharge against the inside surfaces of the upper walls of conduits 42 so that air introduced inside distributing conduits 46 passes outwardly through distributing passages 47 and then flows around both sides of the exterior of the distributing conduits 46 along the external threads thereon and into the balance of the interior space of conduits 42.

As seen in cross section in FIGURE 10, `one end of each of the distributing conduits 46 is closed and sealed as by plug 48. The opposite ends of each of conduits 46 open into a short transverse plenum 49 located at one end of the burner. Air is supplied to plenum 49 through stub pipe 50, for example, and any other suitable means. As seen in FIGURES 9 and 10, the distributing conduit 46 in each of the parallel conduits 42 comprising air manifold 40 passes through one of the two shorter transverse hollow conduits 43 and into plenum 49 located adjacent thereto. Each conduit 46 is provided with a distributing passage 47 extending substantially the length of the distributing conduits and preferably terminating axially between and some point short of the two shorter transverse hollow conduits 43 of the manifold.

As in the burner shown in FIGURES 1 through 8, the interconnection of the corresponding opposite ends of the two long hollow conditions 42 by the shorter hollow conduits 43 tends to insure the good equalization of air pressure from end to end from side to side within the air manifold. The inclusion of externally-threaded distributing conduits 46 as described above within the longer hollow conduits 42 also tends to insure equalization of the air pressure from end to end in each side of the air manifold 40. There is also a cooperation between distributing conduits 46 and hollow conduits 42 that is much the same u as that described in connection with distributing conduit 28 and hollow conduit 23 in gaseous fuel manifold 11 of the burner shown in FIGURES l through 5. As in gaseous fuel manifold l1 of the FIGURES l through 5 burner, distributing conduits 46 and their surrounding conduits 42 cooperate to provide longitudinally extending corner chambers Sl comprising pressure-equalizin g and cross-connecting passage intermediate the beginning and end of the circumferential flow passages between the external threads of the distributing conduits.

The invention, as embodied in the burner shown in FIGURES 9 through l1, is not limited to air manifolds in which the distributing condiuts are located in the upper portions of the longer hollow conduits of the air manifolds. For example, the distributing conduits may lengthwise of the longer hollow conduits in a position parallel to and substantially laterally opposite the air discharge passage provided in the hollow conduit side walls for supplying air to the combustion zone. In such case, the distributing passages in the distributing conduits are preferably faced away from the discharge slots in the hollow conduits in the same manner that distributing passage 29 is faced away from inlet passage 25 in gaseous fuel manifold 11 shown in FIGURE 5. Such an arrangement of the distributing conduit within the longer hollow conduit places the guiding and channelling influence of the external threads on the distributing conduit closely adjacent the inlet passage from the hollow conduit to the combustion zone so that the threaded portions tend to direct the air entering the inlet zone at all points along the length of the inlet passages in a direction substantially directly across the combustion zone.

It will be equally apparent that the distributing conduits may be located in the lower part of the conduits making up the air manifold. When the elements are so arranged, the distributing passage or slot extending substantially the length of the distributing conduit is preferably faced toward the inside surface of the lower wall of the hollow conduit.

One of the principal advantages of the air manifold employing externally-threaded hollow distributing conduits as shown in FIGURES 9 through l1 is that it permits the use of an easily-provided slotted inlet passage entering combustion zone 45, In the form of burner shown in FIGURES l through 5, air is discharge from the air manifold in the combustion chamber through a plurality of small, closely spaced inlet passages in the walls of the hollow conduits. A plurality of air inlet passages carefuly aligned transversely of the combustion Zone tend to reduce and/ or eliminate any tendency of the incoming air to blow the flame toward one end or the other of the burner. Absent the externally-threaded hollow distributing conduits within the longer hollow conduits comprising the air manifold, a simple slotted inlet passage into the combustion zone provides air llow tending to blow the flame therein toward the end or ends of the burner. Distributing conduits used in connection with slotted inlet passages materially reduce and tend to prevent the incoming air from blowing the flame toward one end or another of the burner by blocking and/or redirecting most undesirable components of velocity of the air.

The gaseous fuel manifold 41 is comprised of a single longitudinally extending hollow conduit 52 and an externally-threaded hollow distributing conduit 53. Conduits 52 and 53 are provided with an inlet passage 54 and a distributing passage 5S, respectively, arranged and related to each other in the same manner as are the corresponding elements of gaseous fuel manifold l1 of the buner shown in FIGURES 1 through 5. Gas manifold 41 comprises one side of the combustion zone. Gas is supplied to the manifold through stub pipe 56 and is distributed to the combustion zone for combustion in the same manner as it is handled in gaseous fuel manifold 1l in the burner rst described above.

FIGURE 12 shows a modification of burner construe tion as seen in a cross-sectional view. The burner of FIGURE 12 is generally the same as the other burners described above in that air and gaseous fuel are separately supplied to a combustion zone formed between two parallel, laterally spaced air conduits with a single gaseous fuel conduit lying between them. As seen in FIGURE 12, the longitudinally extending air conduits 60 have externally-threaded hollow distributing conduits 61 fitted within them. Air conduits 60 are of circular cross section and have an inside diameter which closely accepts the distributing conduits 61. Each cooperating set of air conduits 60 and distributing conduits 61 is provided with an inlet passage 62 in air conduit 60 for discharging air into the combustion zone and a distributing passage 63 in distributing conduit 6I. Inlet and distributing passages 62 and 63 are oppositely directed as shown in FIGURE l2 and, together with the cooperating fit between the two conduits, -require air supplied in the hollow interior of distributing conduit 61 to pass first outwardly and away from the combustion zone through distributing passage 63 and thence circumferentially in both directions around the outside of distributing conduit 61 and inside of air conduit 60 to inlet passages 62 for discharge into the combustion zone. Both inlet passages 62 and distributing passages 63 are preferably and easily formed as continuous slots. In spite of the continuous longitudinal extent of the inlet passage, incoming air discharged into the combustion zone therefrom is directed substantially transversely of the combustion zone by the guiding and channelling inuence and effect of the threaded distributing tubing or conduit. The slotted inlet passage tends to be oriced by the threaded distributing tubing or conduit.

The gas manifold is formed of a cooperating, longitudinally extending conduit 65 and externally-threaded dis tributing conduit 66 fitted together in the same manner as the cooperating conduits 60 and 61 of the air manifold.

The two air manifold conduits 60 and the gas manifold conduit 65 can be conveniently and easily arranged and welded together into the relationship shown in FIGURE l2. It will be noted that the inlet passages 62 in the two air conduits 6G are directed at each other across the combustion zone between them and that the inlet passage 67 in gas conduit 65 is directed normal to inlet passages 62 and toward the open face of the combustion zone.

As shown in FIGURE 12, the upper side walls of the combustion zone are preferably formed of longitudinally extending angle sections 7G, arranged as shown, to provide upper vertical side walls 71 for the combustion zone. While burners without angle sections 70 have been Successfully operated, the flame formation is improved by their addition. The curvature of the air conduits 60 seems to encourage the flame to slide off on one side or the other of the combustion Zone and burn without a thorough mixing of the air and gaseous fuel.

In the cross section of the burner shown in FIGURE 12, air and gas conduits 60 and 65 have been shown as circular in cross section. Square cross section tubing, such as employed in the gaseous fuel manifolds of the burners described above, may be employed with highly satisfactory results. Also, in the burner of FIGURE 12, the air gas conduits are of equal diameter. It will be apparent that the relative diameters may b'e varied to accommodate particular operating conditions and/or dimensions.

In connection with all of the burners shown and described, the distributing conduits of two of them have been characterized as being externally threaded. Such externally threaded tubing or conduit is commercially available and easy to obtain; however, it is not necessary to the successful practice of this invention that the external surface of the distributing conduit be provided with a helical thread. Circular fins or grooves will also satisfactorily perform the function `of the external threads, and the terms externally threaded or external threads It) or the like are intended to comprehend conventional circular fins, ribs, or grooves as well as external helical threads.

Those skilled in the art will appreciate that various other changes and modifications can be made in the preferred form of apparatus described herein without departing from the spirit and scope of the invention.

We claim:

1. A gaseous fuel burner comprising:

a combustion zone,

an air manifold for supplying primary air to the combustion zone and a gaseous fuel manifold for supplying gaseous fuel to the combustion zone,

said air manifold having two longitudinally extending, parallel spaced apart, longer hollow conduits connected together at their adjacent ends by and their hollow interiors placed in communication at both ends through two shorter transverse hollow conduits, supply means in said manifold for introducing a supply of air therein and air inlet means along the length of said hollow conduits for supplying and distributing air to said combustion zone, said outlet means in each of said conduits being directed to a laterally opposite conduit and the outlet means therein,

said gaseous fuel manifold having a single longitudinally extending hollow conduit lying parallel to and laterally offset in the space between said longitudinally extending and said shorter transverse conduits of said air manifold, supply means in said manifold for introducing a supply of gaseous fuel therein, and gaseous fuel inlet means in said hollow conduit extending substantially the length thereof for supplying and distributing gaseous fuel to said combustion zone, said gaseous fuel inlet means being directed generally normal to the direction of said inlet means in each of said air manifold conduits and out through the space between said air manifold conduits,

said gaseous fuel and air manifolds cooperating to form said combustion zone, said zone being generally longitudinally co-extensive with said gaseous fuel manifold and extending laterally between said two longitudinally extending air manifold conduits and having a longitudinally extending open face laterally opposite said gaseous fuel manifold.

2. Appartus according to claim 1 in which said gaseous fuel manifold comprises a side wall facing outwardly of said combustion zone from between said two conduits of said air manifold, said gaseous fuel inlet means in said gaseous fuel manifold comprising a longitudinally extending slot in said outwardly facing side wall, a longitudinally extending hollow conduit co-extensive in length with said gaseous fuel manifold lconduit and mounted coaxially therein and in communication with said gaseous fuel supply means, said interiorly and coaxially mounted hollow conduit having a longitudinally extending distributing slot directed in the radially opposite direction from the direction of said gaseous fuel inlet means in said outwardly facing wall of said gaseous fuel manifold.

3. Apparatus according to claim 2 in which said interiorly and coaxi'ally mounted hollow conduit comprises an externally-threaded hollow tube, the outside diameter of said exterior threads being great enough to reach across the interior dimension of said gaseous fuel hollow conduit in at least one direction whereby gaseous fuel supplied to said interiorly and coaxially mounted conduit is distributed from said -longitudinally extending distributing slot therein and passes tto said gaseous fuel inlet means in said gaseous fuel manifold along a path between the threads `on the exterior of said interiorly mounted conduit.

4. Apparatus according to claim 3 in which said gaseous fuel manifold has a hollow interior of generally square transverse cross section and said interiorly mounted hollow tube has an outside diameter insuring contact between the exterior of said tube and the interior of said conduit in the region of the midpoints of side walls of said conduit interior whereby four longitudinally extending chambers are provided in the corners of said gaseous fuel conduit and externally of said coaxially mounted tube.

5. Apparatus according to claim 1 in which said air manifold comprises a hollow conduit of generally rectangular cross section and said gaseous fuel manifold comprises a hollow conduit of generally square cross section.

6. Apparatus according to claim 1 in which said air supply means to said air manifold is provided in one .of said short transverse hollow conduits for supplying air to said manifold at one end thereof.

7. Apparatus according to claim 6 in which said supply means to said gaseous fuel manifold is provided at one end thereof.

8. Apparatus according to claim 7 in which said supply means for said air manifold and said supply means for said gaseous fuel manifold enter their respective manifolds generally adjacent the same end of said burner.

9. Apparatus according to claim 1 in which said air inlet means in each of said longer hollow conduits comprising said air manifold for supplying and distributing air to said combustion chamber comprises a parallel pair of rows of holes spa-ced apart throughout their length with the holes in one row staggered with respect to the holes in the other and in which the air inlet means in each of said shorter transverse hollow conduits comprises a single centrally located hole directed inwardly toward and axially of said combustion Zone.

10. Apparatus according to claim 9 in which said rows of holes comprising said air inlet means in said longitudinally extending hollow conduits are aligned parallel to said gaseous fuel conduit and spaced therefom a distance approximately half of the transverse dimension of said combustion Zone.

11. A gaseous fuel burner comprising:

a walled and partially confined combustion Zone, said combustion Zone being substantially much longer than `wide and having a longitudinally extending open face,

gaseous fuel inlet means extending longitudinally along the length of said combustion zone and in :that side thereof opposite said open face for introducing and distributing gaseous fuel in uniform quantities throughout the length of said combustion zone, and

air inlet means extending longitudinally along the length of said combustion zone and on both sides of said gaseous fuel inlet means and between said gaseous fuel inlet m'eans and said open-face of said combustion zone for introducing and distributing air in uniform quantities throughout the length `of said combustion zone and for thoroughly mixing air and gaseous fuel.

12. Apparatus according to claim 11 in which said pair of air inlet means extending longitudinally along the length of the combustion zone on both sides of said gaseous fuel inlet means are joined together at opposite ends of the burner and have an air supply connection means at one end thereof.

13. Apparatus according to claim 11 in which said gaseous fuel inlet means comprises inner and outer coaxially related conduits closed at their ends, gas supply connection means in communication with said inner conduit, a longitudinally extending passage means in one side of said inner conduit, and a longitudinally extending passage means in that side of said outer conduit diametrically opposite the passage in said inner conduit, said air inlet means comprises inner and outer coaxially related 12 conduits, air supply connection means in communication with each of said inner conduits, a longitudinally extending passage means in one side of each of said inner conduits, a longitudinally extending passage means in that side of each of said outer conduits diametrically opposite said passage means in its coaxially related inner conduit.

14. Apparatus according to claim 11 in which said air inlet means comprises a pair of parallel spaced apart and longitudinally extending longer hollow conduits and a pair of shorter transverse hollow conduits joining together the adjacent ends of said longer conduitsso that the passages in said hollow conduits comprise a complete continuous path and means substantially midway of the length of one of said shorter transverse 4conduits for introducing air into said air inlet means.

15. Apparatus according to claim 11 in which said air inlet means comprises parallel spaced apart and longitudinally extending pairs of hollow inner and outer conduits, air supply connection means in communication with said inner conduits longitudinally aligned and extending passage means in a side of each of said inner conduits and facing in one direction, a longitudinally aligned and extending passage means in a side of 'each of said outer conduits and facing in another direction and across said combustion zone to said passage means in the other of said outer conduits.

16. Apparatus according to claim 15 in which said inner conduits comprise exteriorly-threaded pipes of circular cross section, each having an outside diameter substantially equal to the least internal dimension of its associated conduit.

17. Apparatus according to'claim 16 in which each of said passage means' in said inner and outer conduits face in diametrically opposite directions and each of said conduits overlies said inlet passage in its associated -outer conduit and said exterior threads of said inner conduits transversely divide and orifice said inlet passages in said outer conduits.

18. Apparatus according to claim 11 in which said gaseous fuel inlet means comprises inner and outer coaxially related conduits closed at their ends, gas supply connection means in communicaiton Iwith said inner conduit, a longitudinally extending passage means in one side of said inner conduit, and a longitudinally extending passage means in that side of said outer conduit diametrically opposite the passage in said inner conduit.

19. Apparatus according to claim 14 in which said gas supply connection means comprises a longitudinally 'extending plenum substantially coextensive with said inner conduit, gaseous fuel inlet means in said plenum and a plurality of gaseous fuel passage interconnecting said plenum and said inner conduit and spaced apart along their coextensive lengths.

2t?. Apparatus according to claim 18 in Which said inner conduit comprises an exteriorly-threaded pipe of circular cross section having an outside diameter substantially equal to the least internal dimension of said outer conduit.

21. Apparatus according to claim 20 in which said outer conduit is of generally square cross section, the distance between the sides of which are approximately equal to the outside diameter of said inner conduit so that sai-d two coaxially related conduits are generally in engagement at the points of tangency of said inner conduit and the interior of said outer conduit and out of engagement at the corners of said outer conduit.

References Cited by the Examiner UNITED STATES PATENTS 2,398,884 4/1946 Crawe 239-544 FOREIGN PATENTS 672,166 9/1929 France. 1,052,499 9/1953 France.

EVERETT W. KIRBY, Examiner. 

11. A GASEOUS FUEL BURNER COMPRISING: A WALLED AND PARTIALLY CONFINED COMBUSTION ZONE, SID COMBUSTION ZONE BEING SUBSTANTIALLY MUCH LONGER THAN WIDE AND HAVING A LONGITUDINALLY EXTENDING OPEN FACE, GASEOUS FUEL INLET MEANS EXTENDING LONGITUDINALLY ALONG THE LENGTH OF SAID COMBUSTION ZONE AND IN THAT SIDE THEREOF OPPOSITE SAID OPENING FACE FOR INTRODUCING AND DISTRIBUTING GASEOUS FUEL IN UNIFORM QUANTITIES THROUGHOUT THE LENGTH OF SAID COMBUSTION ZONE, AND AIR INLET MEANS EXTENDING LONGITUDINALLY ALONG THE LENGTH OF SAID COMBUSTION ZONE AND ON BOTH SIDES OF SAID GASEOUS FUEL INLET MEANS AND BETWEEN SAID GASEOUS FUEL INLET MEANS AND SAID OPEN FACE OF SAID 